Carburetor



Ma 31, 1 938. E, SCHWNE'K 2,118,947

CARBURETOR Filed Jan. 31, 1935 2 Sheets-Sheet 1 17722-02 ,'cka'manek I I INVENTOR BY I 2 ATTORNEY May 31, 1938. E. SCHIM'ANEK 2, CARBURETOR I Filed Jan. 31, 1935 2 Sheets-Sheet 2 l'mz'Zdohima/nek INVENTOR Patented May 31, 1938 UNITED STATES PATENT OFFICE I cannunn'roa Emil Schimanek, Muegyetem, Budapest, Hungary Application January 31, 1935, Serial No. 4,253

, In France February 1 1934 10 Claims. (01. 261 48) 10 The carburetor according to the invention warrants such a constant fuel supply to the fuel orifice or nozzle, whatever the conditions of flight and the pressure variations of the supplying source may be.

15 The invention consists in that the fuel supply to a calibrated opening or nozzle of the carburetor is regulated by means of a movable member, such as for instance a slider, the movement of which is determined by a system of twomem- 2 branes or diaphragms with different surface areas, which are subjected, on the one side, with their adjacent surfaces to the, preferably constant partial vacuum on which the admission'of the air is dependent, and on, the other side, to the con- 25 stant pressure of the fuel.

Fig. 1 shows the carburetor carried out according to the invention in vertical section, and Fig. 2 a partial section through another modification.

The body I of the carburetor isprovided with 30 an air inlet 2, and a discharge passage 3 for the combustible mixture which is connected with the inlet of the motor. By means of the throttle valve 4, the power of the motor can be regulated.

In the" upper part of the carburetor body a 35 cylinder 6 is arranged in which a piston I is movable which is pushed downward by a spring III thus acting in the same direction as the weight of the piston. This piston 1, according to its position in the cylinder 6, closes up more or less 40 an opening H which forms the communication between the space 31 of the combustible -discharge socket 3 and the space ll of the air inlet 2. At the bottom of the piston l, a needle is attached in such a manner that it is adjustable as to its height. This can be accomplished, for instance, by screwing the threaded end 8 of the 'needle into a corresponding thread in the bottom of the piston and securing it by nut 9. The 50 needle 5 extends through a channel in the body I of the carburetor which channel ,is provided with two cylindrical enlargements l5 and 41 communicating with each other through a calibrated opening I2. The needle 5 passes through this 55 opening and closes it up more or less with its conical part 5a, according to the height-position of the piston I. g

A conduit 42' opens into the upper part 41 of the channel at its lower end adjacent the calibrated opening l2, which conduit communicates through openings 42 with the space 31 of the discharge passage 3. Further, the cylindrical part 4 of the channel opens through its upper open end into the space 4| of the air inlet.

The pressure reduction regulator is constructed 0 as follows:

In the cylindrical part IS a tube-like slider I4 is slidably arranged and supported by two diaphragms l6 and It, the surfaces of which have different areas. These diaphragms are fastened in a bell-shaped lower part of the carburetor body I.

The fuel is supplied by means of a pump or from a higher located reservoir or from a reservoir under pressure, through the conduit l3 to the carburetor, via the cylindrical part l5 of the same, into the upper part 23 into which a conduit orchannel 19' opens at one end and terminates' at its other end in a socket l3 serving as over-flow for the fuel. 25

As can. be seen from the drawing, .the slider Id, at the same time, governs the fuel supply through the conduit l3 and the outflow of the surplus of the fuel through the conduit l3. The length of the slider I4 is such that the fuel only can flow through the conduit [3 and the opening 22 in the slider into the interior of .the slider and into the calibrated opening l2 when the conduit l3 to the over-flow is shut off.

At the lower end of the slider M a cylinder 25 is arranged which is closed by a bottom 25a and in which a piston 26 with valve-flaps 21 is slidable. By thismeans a braking or damping for the movement of the needle system is provided. I A'conduit 3la between the sockets 3| connects 40 the space 32 between the two diaphragms with the space 39 between the cover of the cylinder 6 and the piston I, while another conduit between the sockets 35 and 36 establishes the communication between the space 3'l beneath the larger diaphragm l6, and the space M of the air inlet 2. By reason of this construction there exists the same partial vacuum above the piston I and in the space 32 between the diaphragms, and the same-pressure below the piston I and below the larger diaphragm IS.

The carburetor operates as follows: When the motor is at rest the pressure in the space 32 between the two diaphragms is just the same as the pressure in the spaces 34 and 24,

' of the arrow 4|].

The difference between the pressures which exist, on the one'hand, in the space 38 above the piston 1 and, on the other hand, below the piston I, has just the required magnitude in order to balance the weight of the piston 1 augmented by the pressure of the spring Ill and the weight of the parts connected to the piston. The pressure of the spring is substantially constant owing to a sufficiently-great number of windings which form the spring. Under these conditions the difference in pressure between the space 4|, on the one side, and the spaces 39, 31, on the other side, will be: constant, whatever the load and the number of revolutions of the motor may be. Therefore, the air will always flow under the influence of the same pressuredifference through the carburetor in the direction of the arrow ll.

When the load or the number of revolutions of the motor increases, the piston 'I will rise higher and higher, and a greater amount of air can flow through the carburetor under the same pressure-difference, that is with the'same velocity.

The air takes the following two ways: firstly, one way through the pre-carbureting stage, by

which the air enters from the space H in the direction of the arrow 43 into the interior of the central channel I! and mixes there, flowing in the direction of the arrow 4,5, with the fuel coming out of the calibrated opening;and'second-' ly, another way in the direction of the arrow 4|,

by which the air from the space 4| mixes with the mixture coming through the openings 42 and thereby thoroughly whirls it through.

The velocity of the air current through the channel 4'! may be regulated by changing the entrance-area of the same, .for instance by inserting rings 48 with different inner diameters.

The fuel reaches by the following path the calibrated opening l2: The partial vacuum in the cylinder space 35 above the-piston I is communicated through the conduit am to the space 32 between the two diaphragms l6 and it. 'Since the diaphragm I5 is greater than the diaphragm IS, the slider I4 is lifted and thereby first closes the over-flow conduit I 9' and then opens the fuel supply conduit l3 as soon as the holes 22 are in alignment therewith.

The pressure of the fuel in the space 24 increases till it preponderates, whereby the diaphragm I6" is pressed downwards so that the slider H tendsto shut off the fuel supply. Thereupon a balance position of the slider ensues,

whereby the fuel pressure is regulated to a confuel is fed through the calibrated opening I 2 in consequence of the constant pressure-difference mentioned above.

When the motor comes to a standstill the partial vacuum in the space 32 disappears; the slider sinks and, after having shut-off the fuel supply conduit, opens the over-flow conduit l9,

whereby the space 23 is put under atmospheric pressure.

The braking or damping cylinder 25 connected to the diaphragm I6 has the following task: If the throttle valve 4 is rapidly opened the motor starts again, and the partial vacuum in the space '39 above the piston I instantaneously rises.

This increase of the partial vacuum tends to suddenly lift the piston 1, which movement the piston 26 (provided with valves) at the'lower end of the needle 5 tends to counteract in forc- 1 ing upwards the fuel contained in the space 30. This pressure is transmittedto the upper cover of the cylinder space 30- and effects the lifting thereof and therewith that of the slider ll, whereby, on the other hand, the opening of the fuel supply conduit l3 isfurther opened and, on the other hand, the pressure in the space 23 is raised. This has theeffect that a larger amount of the fuel passes through the calibrated opening l2, so that a very effective re-starting of the motor can be attained.

Such an effect of the piston 28 does not occur if the piston moves downwards, because thereby the valve-claps open entirely and the fuel can flowwithout resistance through the piston provided with the valves.

Moreover, the braking which the piston I, when sinking, experiences by the damping, though only to a small extent, tends to force the slider l4 downwards and to partially shut off the fuel supply conduit I 3, whereby the retarding of the motor is favoured.

In the modification of the carburetor according to the invention shown in Fig. 2, the overflow conduit IQ of Fig. 1 has been omitted, and the interruption of the fuel supply is effected by the needle by means of its particular formation,

one portion 55 of the needle taking over the function of 'a clap or a valve. This portion becomes seated with its lower surface on a seat 5| and thus shuts off the calibrated opening l2.

While the motor is running the needle 5 is lifted and the valve portion 55 is raised from itsseat so that the fuel can flow through the opening II. The slider H, in this case, regulates the fuelsupply solely through the conduit l3.

It is to be understood that modifications in particulars of the construction may be designed without departing from the spirit of the invention. In particular, a throttle valve 4' may be placed in the air inlet 2 and either the valve 4 or the valve 4' may be omitted if desired.

What I claim is:

1. In a carburetor for an internal combustion engine, an air inlet, a fuel inlet, a fuel chamber, a mixing chamber, a nozzle between the fuel inlet and chamber, a device for regulating the fuel supply through said nozzle, said device including diaphragms having pressure surfaces of different sizes to produce a differential action, the diaphragm having the smaller size pressure surface being subjected 'on one side to the pressure of the fuel in the fuel chamber and forming a wall of said chamber and being subjected on its other side to the partial vacuum set up by the engine.

2. A carburetor comprising a main housing having an air inlet, a fuel inlet, a fuel chamber, a mixing chamber, a passage from said -mixing chamber to the ,engine and a device for regulating the flow of fuel to said mixing chamber, said device including a cylindrical casing on the top ofthe housing, a tubular member adapted to cut off communication between the fuel inlet and the fuel chamber, another cylinder carried on the lower end of the tubular member and in communication with the fuel chamber, a piston in said first cylinde under the influence of a spring in said cylinder chambe a stem depending from said piston, another piston at the lower end of said stem movable in the second cylinder, an auxiliary housing carried on the lower end of the main housing, spaced. diaphragms dividing said auxiliary housing into upper, lower and intermediate compartments, the upper compartment being in communication with the fuel inlet, the intermediate compartment being in communication with the passage leading to the engine and the lower compartment being in communication with the air inlet, said diaphragms having pressure surfaces of different sizes whereby they are actuated by varying pressure conditions.

3. In a carburetor, a main casing having an air inlet, a fuel inlet, a fuel chamber, a mixing chamber and an'outlet to the engine for the mixture, a tubular member for controlling the flow of fuel to the mixing chamber, an auxiliary casing fixed to the lower end of the main casing, spaced diaphragms fixed to the tubular member dividing said latter easing into upper, lower and intermediate compartments, one of said compartments being in communication with the air inlet, another of said compartments being in communication with the suction side of the engine, and another of said compartments being in communication with the fuel inlet and forming part of the fuel chamber and a piston under the influence of the suction of the engine for partially controlling the fiow of air and fuel.

4. In a carburetor, a main casing having an air inlet, a fuel inlet, a fuel chamber, a mixing chamber and an outlet to the engine for the mixture, a tubular member for controlling the fiow of fuel to the mixing chamber, an auxiliary casing fixed to the lower end of the main casing, spaced diaphragms fixed to the tubular member dividing said latter casing into upper, lower and intermediate compartments, one of said compartments being in communication with the air inlet, another of said compartments being in .communication'with the suction side of the engine, and another of said compartments being in communication with the fuel inlet and forming part of the fuel chamber, a piston under the influence of the suction side of the engine for partially controlling the flow of air and fuel and means for damping the movement of said piston, said means including a piston on the lower end of the stem of the first named piston and movable in the fuel.

5. A carburetor comprisinga main casing having an air inlet, a fuel inlet, a fuel chamber, a mixing chamber and a passage from said mixing chamber to the engine, an auxiliary casing fixedto thebottom of the main casing, mechanism for regulating the flow of fuel to the mixing chamber including a movable tubular member having openings adapted to align with the fuel inlet, a pair of pressure responsive diaphragms fixed to said tubular member at spaced intervals for dividing said auxiliary casing into upper,

lower and intermediate compartments, one of said diaphragms having a larger pressure surface than the other diaphragm, .said upper compartment being in communication with the fuel chamber, said intermediate compartment being in communication with the engine passage and said lower compartment being in communication with the air inlet, mechanism for partially regulating the flow of air and fuel to the engine passage including a chamber disposed between the air inlet andengine passage and being in constant communication with said passage, a piston movable in said latter chamber and normally closing communication between the air inlet and engine passage, a spring loaded on said piston to keep it in normal position, a stem depending from said piston and extending into the air chamber below the larger diaphragm and adapt-,

ed to curtail the flow of fuel to the mixing chamber, a chamber formed in the lower end of the movable tubular member and being in communication with -the fuel chamber, a piston on the lower end of said stem and movable in said last named chamber against the fluid pressure for damping the movement of the first piston.

6. .A carburetor comprising a body having an air inlet, a fuel inlet, a mixing chamber, a nozzle for the fuel, a fuel pressure regulating member including a slider and spaced diaphragms having pressure surfaces of different sizes for effecting the action of said slider, the movement of said diaphragms being influenced by the difference between the partial vacuum prevailing in the carburetor and atmospheric pressure, said member being adapted to keep constant the fuel pressure in front of the nozzle and means forvarying said partial vacuum.

7. In" a carburetor," an air inlet, a fuel inlet, a

' mixing chamber, a nozzle disposed between the vacuum, and one of said surfaces on the other side of oneof said diaphragms being subjected to fuel pressure, the other of said diaphragms being subjected on its opposite side to a pressure greater than the'pressure between said spaced diaphragms.

8. A floatless carburetor comprising an air inlet, a fuel inlet, a nozzle for the fuel, a pressure regulating member for the fuel in front of said nozzle, an automatic throttling device disposed in said air inlet and dividing said air inlet into two spaces, said throttling device being influenced on the one hand by the atmospheric pres-. sure prevailing in the space of the air inlet in front of the throttling device and on the other hand by the under pressure prevailing in the space of the air inlet behind said throttling device causedby the suction of the engine and means for imparting said difference in pressure between said spaces to said pressure regulating member for the fuel, said pressure regulating member being actuated by said pressure difference.

9. A fioatless carburetor as claimed in claim 8 in which the throttling device comprises a piston acted upon on the one side by the atmospheric pressure prevailing in the space in front of the throttling device and on the other side by the .under pressure prevailing in the space behind the tling device disposed in the air inlet and dividing said air inlet into two spaces, said throttling device being influenced on the one hand by the atmospheric pressure prevailing in the space of the air inlet in front of the throttling device and on the other hand by the under pressure prevailing in the space of the air inlet behind said throttling device caused by the suction of the engine thereby keeping constant the difference between the pressures prevailing in the said spaces and means for imparting said constant pressure difference to said device for regulating the fuel 10 supply through said nozzle.

EMIL SCHIMANEK. 

